<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script>
        var num = 1;
        num = num + 1;
        num = num + 1;
        console.log(num);
        // 2.前置递增运算符   ++ 写在变量的前面
        var age = 10;
        ++age;//类似于  age = age+1
        console.log(age);
        // 3.先加一  后返回值
        var p = 10;
        console.log(++p + 10);
    </script>
</head>
<body>
    
</body>
</html>